Directional-action mechanical vibrators are known in the art, such as crank-type ones. These vibrators comprise a crankshaft carrying a number of inertia masses arranged eccentrically thereon, said crankshaft being accommodated in a housing and linked to a drive. A rod is coupled with one of its ends to the crankshaft and with the other end, to the mass being vibrated, whereas the vibrator housing is fixed in place on the frame of the mass being vibrated. Such vibrators impart fixed-amplitude directional oscillating motion to the mass being vibrated but, however, fail to adequately balance the forces of inertia developed by said mass.
Application in such vibrators of additional shafts carrying inertia masses eccentrically arranged thereon and linked to the crankshaft through gearings, makes it possible to provide for a better balancing of the forces of inertia. However, this complicates the construction of the vibrators very much.
Some other directional-action mechanical vibrators are also known (cf., e.g., Swedish Pat. No. 921,231). Such a vibrator is of the single-shaft inertia-type mechanism and comprises a shaft carrying a number of inertia masses arranged eccentrically thereon, said shaft being accommodated in a housing, and a rod that imparts motion to the mass being vibrated is locked-in with the housing. When the shaft of the abovesaid vibrator rotates, inertia masses arranged eccentrically thereon develop a force of inertia which imparts a directional reciprocating motion to the mass being vibrated and a pendulum motion to the vibrator housing in a direction normal to that of the reciprocating mass. Thus, almost complete balancing of the inertia forces is attained. Such a directional-action vibrator is simpler in construction than multiple-shaft crank-type directional-action vibrators. However, inasmuch as the amount of amplitude of the mass being vibrated depends upon the magnitude of said mass, it varies with a change of the latter. This phenomenon occurs when the known vibrator is employed in diverse separating machinery, jigging conveyers, etc. under variable rate of charging with a loose material. This results, in the case of separating machines, in affected operating quality thereof, as optimum kinematic conditions of the separating process are impaired. Apart from this disadvantage the known vibrator also suffers from another disadvantage which, due to the vibrator housing being held to the mass being vibrated, it performs reciprocating motion along therewith, involves extra loads upon the bearing structures of the mass being vibrated and adds to power consumption.
Known in the present state of the art are some mechanical systems for converting rotary motion into reciprocating motion (cf., e.g., Accepted Application of the Federal Republic of Germany, No. 1,558,844). Such a system comprises a single-shaft inertia-type vibrator whose housing is made fast directly on the spring-opposed mass being vibrated. The vibrator shaft is accommodated in the housing and rests upon two supports, while an inertia mass is arranged eccentrically on said shaft between the supports thereof, and additional inertia masses are movably and eccentrically mounted on the shaft beyond the supports thereof. One of the shaft ends mounts a pulley whose axis aligns with that of the shaft, said pulley being linked, through a V-belt, to another pulley set on the electric motor shaft. The axis of the motor shaft and that of the vibrator shaft are coplanar, their plane being normal to the direction of reciprocating motion performed by the mass being vibrated. When the vibrator shaft rotates the inertia masses arranged eccentrically thereon develop such forces of inertia that the resultant thereof compels reciprocating motion of the spring-opposed mass being vibrated. It is in this way that rotary motion is converted into reciprocating motion in said known mechanical system.